docs(collator): include "id" placeholder in start command example

[olahfemi]

📝 Description

Updated the command example for starting the collator to include a placeholder for the "id". This ensures the path is properly created and detected, helping prevent routing and initialisation errors when running the command.

Error if the user doesn't use their "id" in the command:

Test to confirm that the command that starts the collator needs the "id"

You'd see in the screenshot above that, even though the parachain name is Ethereum, the collator still starts since I used the id name in the path. This is because the Polkadot Omni node uses the "id" to create the base path for storing the node key.

🔍 Review Preference

Choose one:

• ✅ I have time to handle formatting/style feedback myself
• ⚡ Docs team handles formatting (check "Allow edits from maintainers")

✅ Checklist

• Changes tested
• PaperMoon Style Guide followed

[eshaben]

Applied minor formatting changes to adhere to our style guide. @0xlukem can you pls sign off on this?